A fiber laser is a type of optical laser that includes a clad fiber rather than a rod, a slab, or a disk. Fiber lasers reflect light through an optical cavity such that a stream of photons stimulates atoms in a fiber that store and release light energy at useful wavelengths. Fiber type, core size, numerical aperture, refractive index, and doping of the fiber contribute to the range and possibilities of light propagation using fiber lasers.
A fiber laser 100 is shown in FIGS. 1A and 1B. Fiber laser 100 may include a core 102 surrounded by a cladding 104 and a protective coating 106. Core 102 may have a different refractive index than cladding 104. Depending on size, refractive index, and wavelength, core 102 may be single mode or multi-mode although single mode is preferred for many applications. Core 102 may be made of a variety of materials including well-known silica-based materials. Core 102 may include a dopant 103 from the lanthanide series of chemicals including Erbium or Ytterbium that release light energy at useful wavelengths. Fiber laser 100 may be illuminated by a light source 110, e.g., a laser pump including a laser diode element driven by a laser diode driver with a corresponding control unit. Light source 110 may be a single diode, an array of diodes, or many separate pump diodes, each with a fiber going into a coupler. Fiber laser 100 may further include a grating 114 at both ends of coil 111 to manipulate or otherwise filter light source 110 and deliver it as a laser beam 116. Fiber laser 100 may be used in a variety of applications including welding heavy sheets of metal, cutting high-strength steel used to produce automobiles, cutting and drilling concrete, and microscale and nanoscale machining.
In some applications, fiber laser 100 may have a length between several millimeters and hundreds of meters, most commonly in the 1-30 meter range. Fiber laser 100 may be coiled 111 with a generally permissible bend radius in the 10-20 millimeters. Fiber laser 100 may release heat during operation that requires efficient heat removal to avoid damaging core 102 or cladding 104.
Fiber laser 100 may fail or malfunction after deployment to a customer's site for a variety of reasons including failure of any or a combination of components included in light source 110. Fiber laser 100, particularly light source 110, may be built using modular components that allow failure remediation by disabling or replacing some of the modular components to allow fiber laser 100 to continue operating at least at a reduced power level.
Additionally, spurious sensor readings at light source 110 may cause fiber laser 100 to appear to malfunction. The ability to continue operating by overriding or otherwise ignoring spurious sensor readings is desirable.
A need remains for an improved laser fault tolerance and self-calibration system.